Die grinder

ABSTRACT

A grinder includes a drive tube dimensioned to freely receive an elongated, grinding element having an axially extending opening; locking means for releasably locking the grinding element for rotation with the drive tube; and an adapter insert dimensioned to be slideably received within the drive tube and mounting a coaxially extending support and rigidifying mandrel dimensioned to be slideably received within the opening of the grinding element.

Q I C Untte States 1 atent 11 1 1111 3,858,362 Welsch 1 Jan. 7, 1975[54] DIE GRINDER 1,254,071 l/l918 Reinlie 51/206 R 2,359,594 10/1944 T h1k 1 1 .51 170 PT [75] Inventor: Walter Welsch, Tonawanda 2,722,09211/1955 51/403 [73] Assignee: Dynabrade, Inc., Tonawanda, NY. FOREIGNPATENTS OR APPLICATIONS [22] Filed: Feb. 21, 1974 112,910 4/1961 Denmark285/348 [21] Appl Primary Examiner-James L. Jones, Jr.

Related US. Application Data Attorney, g or FirmB6an d e [63]fg7n3tinuation-in-part of Ser. No. 391,686, Aug. 27, [57] ABSTRACT Agrinder includes a drive tube dimensioned to freely [52] US. Cl. 51/170PT, 51/403 receive an elongated, grinding element having an axi- [51]Int. Cl B241) 23/00, 824d 11/00 ally extending opening; locking meansfor releasably [58] Field of Search 51/170 PT, 263, 71, 403, lockingthegrinding element for rotation with the 51/361, 206 R, 206 NF;285/348; 279/] Q, drive tube; and an adapter insert dimensioned to be102, 103 slideably received within the drive tube and mounting aco-axially extending support and] rigidifying mandrel [56] ReferencesCited dimensioned to be slideably received within the open- UNITEDSTATES PATENTS 111g of the gnndmg element- 828,894 8/1906 Martin5l/l65.93 10 Claims, 3 Drawing Figures 1 REFERENCE TO RELATEDAPPLICATION This application is a continuation-in-part of my copendingapplication Ser. No. 391,686, filed Aug. 27, 1973.

BACKGROUND OF THE INVENTION working end thereof to severe vibration orbending conditions. These grinding elements may be in the form of eithera bonded grinding wheel or a cartridge roll formed by winding coatedabrasive material about a forming mandrel.

More specifically, this grinding tool basically comprises a drive tubedimensioned to slideably receive and support a given maximum diametergrinding element, and means for releasably locking the grinding elementfor rotation with the drive tube. As the end of the grinding elementarranged to protrude from the forward end of the drive tube becomesworn, the locking device would be released to permit an additionallength of the grinding element to be withdrawn from within the drivetube.

When it was desired to employ a grinding element having a diametersmaller than the given maximum diameter, it was necessary to employ anadapter assembly including a filler or reducing sleeve dimensioned tofill the space between the drive tube and the smaller diameter grindingelement in order to provide proper external support for the latter. Adrawback of this construction is the requirement that the grinding toolmust be provided with a separate reducing sleeve for each reduced sizegrinding element to be used by the tool.

SUMMARY OF THE INVENTION The present invention relates to the provisionof a single removable adapter, which permits the drive tube of thegrinding tool disclosed in my above mentioned co-pending application toprovide proper support for variously sized smaller diameter grindingelements of the cartridge roll variety. Moreover, the improvedconstruction has been found to offer significantly improved support forthis type of grinding element.

In a modified form of the present invention the adapter may beincorporated as a permanent part of the drive tube.

DRAWINGS The nature and mode of operation of the present invention maybe more fully described in the following detailed description taken withthe accompanying drawings wherein:

FIG. 1 is a partially sectionalized side elevational view of a grindingtool embodying the present invention;

FIG. 2 is an exploded view of that part of the grinding tool includedwithin the area designated as FIG. 2 in FIG. 1; and

FIG. 3 is an exploded view similar to FIG. 2, but showing a modifiedform of the present invention.

DETAILED DESCRIPTION The grinding tool designated as 10 in FIG. 1 issimilar to that described in my co-pending application Ser. No. 391,686,filed Aug. 27, 1973 from the standpoint that it generally includes ahollow metal casing or tool housing 12; a drive assembly or mechanism14; an elongated drive tube 16, which has a front end 16a arranged toextend outwardly through a casing front wall opening 18 and isdimensioned to accommodate an elongated, relatively uniform diametercylindrical grinding element 20; a locking device 22 for releasablylocking or clamping grinding element 20 for rotation with drive tube 16;a ball bearing or other suitable bearing device 24 for mounting drivetube 16 for rotation within casing 12; and a manually operable latchdevice 26, which is fitted within casing bottom wall opening 28 forselectively constraining rotation of drive tube 16 when it is desired tooperate locking device 22.

While, as in my prior construction, grinding tool 10 is not limited tothe utilization of my specific drive assembly, assembly 14 is shown inFIG. 1 for purposes of illustration as including a power source, such asan air motor 30, which is suitably affixed to casing rear wall 32 anddrivingly connected through a casing rear wall opening 34 to a drivepulley 36 arranged within casing 12; pulley 36 being coupled to the rearend 16b of drive tube 16 by means of an endless belt 38. The tension inbelt 38 may be selectively controlled by a casing rear wall mounted belttake up or idler pulley 40. Motor 30 may have any suitable shut off orspeed control, such as may be afforded by a pivotally supported lever42, which is adapted to be squeezed by the hand of an operator duringuse of the grinding tool. Also, the surface of drive pulley 36 and thesurface of drive tube rear end 1612 would preferably be slightly crownedin order to insure proper belt tracking. The illustrated construction ispreferred, since air motor 30 also serves as a convenient hand grip formanipulating tool 10. However, if desired, casing 12 may be shaped todefine a convenient hand grip, such as a pistol grip.

Locking device 22 is best shown in FIG. 2 as including a clamping member50, and a resiliently deformable ring shaped member 52. Clamping member50, which may be characterized as being of a generally cupshapedconfiguration, has an internally threaded rim portion 54 by which it maybe adjustably and removably mounted on drive tube front end 16a and hasan opening 56 extending axially through its radially extending base wallportion 58. The construction of clamping member 50 and ring member 52 ispreferably somewhat similar to that described as an alternative orsimplified locking construction in my co-pending application, exceptthat when a sufficiently soft resiliently deformable material is used informing the ring member, the need for employing cooperating cammingsurfaces to effect deformation thereof into clamping engagement with thegrinding element is eliminated.

Ring member 52 is preferably sized to be snugly fitted within clampingmember 50 forwardly of threaded rim portion 54 and to slideably receivea given size of grinding element 20, whereby to facilitate adjustmentsof the grinding element lengthwise of drive tube 16 when the ring memberis not compressed or deformed. Rubber having about 50 Durometer (Shoe A)may be conveniently employed to form a ring member with a useable lifeunder normal daily use of upwards of about one month. Longer life may beachieved by employing a urethane of from between about 70-90 Durometer(Shoe A), but a ring member formed of this type of material wouldnormally have to be cammed into clamping engagement with the grindingelement.

As will be apparent, when clamping member 50 is moved towards, that is,threaded onto drive tube front end 16a, ring member 52 is clamped oraxially compressed between the clamping member and drive tube front end16a, such that the ring member is radially deformed into surfaceclamping engagement with grinding element 20 intermediate its ends. Bythis means, the grinding element is constrained for rotation with thedrive tube. When clamping member 50 is unscrewed sufficiently to releasering member 52 from deforming clamping pressure, grinding element 20 maybe manually pulled axially outwardly through the ring and clampingmembers for purposes of adjustment, i.e., replacement of the front oroutwardly projecting end of the grinding element as it is worn awayduring use.

Again referring to FIG. 1, it will be understood that latch device 26 isemployed to releasably constrain rotation of drive tube 16, duringthreading and unthreading movements of clamping member 50. To this end,latch device 26 includes a plunger operator 70, which may be manuallydepressed against the return bias of a coil spring 72 for receipt withina drive tube wall aperture 74.

As thus far described, tool is only adapted to employ a grinding elementhaving some given maximum diameter or size permitting it to be properlyslip or slide fit supported within drive tube 16. As a practical matter,the drive tube would be sized to permit a grinding element to be easilyinserted, while at the same time serving to maintain the grindingelement essentially centered within the drive tube during tool operationwhen sidewise grinding pressure is applied to the projecting end of thegrinding element. The grinding element employed with tool 10 may eitherbe in the form of a bonded grinding wheel or a cartridge roll, thelatter being formed by winding or wrapping a coated abrasive materialabout a forming mandrel.

In my prior tool construction, adapter assemblies are provided to afiordproper external support for smaller or reduced diameter grindingelements of both types within drive tube 16. Each of these assembliesincludes a filler or reducing sleeve, which is externally sized topermit it to be slide or slip fit supported within the drive tube andinternally sized to permit a given smaller diameter grinding element tobe slide fit supported therein. Of course, the diameter of the grindingele ment to be used by tool 10 will determine the internal dimension ofthe ring member employed to clamp same for rotation with the drive tube.My prior construction has the advantage that each assembly is capable ofaccommodating both types of grinding elements. On the other hand, it hasbeen found that the nature of a grinding operation or economics oftendictates that a cartridge roll type of grinding element be primarilyemployed.

The present invention has resulted from a desire to minimize the numberof assembly components necessarily provided for a grinding tool insituations where cartridgeroll type grinding elements are to beprimarily employed, and the observation that commercially availablecartridge rolls of various outside or external diameters are normallyformed on a common size forming mandrel, thereby resulting in theirhaving like sized axially extending through openings 20'.

Again referring to FIGS. 1 and 2, it will be understood that the presentinvention is directed towards the provision of a single insert 80, whichmay be removably inserted into drive tube 16 whenever it is desired touse any grinding element of the cartridge roll type having an externaldiameter smaller than that which can be properly supported directly bythe drive tube. Insert includes a sleeve member 82, which is externallydimensioned to be slide or slip fitted within drive tube 16; anelongated mandrel or grinding element support 84; and any suitablemeans, such as a disc 86, which serves to rigidly connect the rear endportion mandrel 84 to the rear end portion of sleeve 82 such that themandrel 84 is coupled for rotation with and extends coaxially of thesleeve member. As a practical matter, it is desirable to provide arelatively closer fit between sleeve 82 and drive tube 16 than thatillustrated in FIG. 1 in order to positively position the sleeve andthus mandrel 84 in a co-axial relationship within the drive tube. Also,it is preferable to form sleeve 82 with the minimum wall thicknesspermitted by structural considerations in order to permit inert 80 toaccommodate a full size range of reduced diameter grinding elements.

The front end'portion 82a of sleeve member 82 is enlarged to define aradially extending rear surface dimensioned to axially abut againstdrive tube front end 16a inwardly of its outer threaded surface and aradially extending front surface arranged to engage ring member 52. Withthis construction, whenever clamping member 50 is threaded onto drivetube 16, ring member 52 is resiliently deformed into frictional surfaceengagement with grinding element 20 and sleeve front end portion 82a isforced into frictional surface engagement with drive tube front end 16a,whereby both the grinding element and insert 80 are coupled for rotationwith drive tube 16.

Mandrel 84 is sized and shaped to permit it to be easily slide fittedwith grinding element opening 20, while at the same time providingproper internal support for such element. Mandrel 84 has a lengthsufficient to extend forwardly beyond sleeve 82 and thus drive tube 16,such that its forward end portion is at least axially co-extensive withring member 52 when tool 10 is in its assembled condition shown inFIG. 1. Preferably, the front end portion of mandrel 84 would extendoutwardly beyond member 50 through a short distance, eg. inch, in orderto provide positive internal support for the grinding elementimmediately adjacent its point of application to a workpiece. As in thecase of my prior tool construction, the internal diameter of the ringmember employed will depend upon the diameter of the grinding element tobe used.

In the present construction, when the outwardly projecting or front endof grinding element 20 has been worn away, clamping member 50 isunscrewed sufficiently to release ring member 52 from deforming pressureand the grinding element is then manually pulled outwardly through thering and clamping members to expose a new length of grinding element.With the present construction, this adjustment may be repeated until thelength of the grinding element remaining is insufficient to permit itsbeing gripped by the ring member. When it is desired to employ a bondedgripping wheel in tool 10, clamping member 50 would be unscrewed fromthe drive tube in order to permit removal of the present adapter.

Reference is now made to FIG. 3, which illustrates a modified adapterconstruction for use with grinding tools, intended only to employcartridge roll type grinding elements. In this form of the invention,sleeve member 82 is dispensed with and mounting disc 86 is employed tocouple mandrel 84' directly to the rear end of the drive tube. Thispermits all diameters of grinding elements to be properly supportedwithin the drive tube. Preferably disc 86 is permanently fixed to boththe drive tube and insert, as for instance by welding, adhesive or thelike. However, if desired, disc 86' may be removably attached, as byscrew threads or other suitable coupling device to either or both of thedrive tube and mandrel in order to permit bonded grinding wheels to beaccommodated within the drive tube.

It is anticipated that bonded grinding wheels may in the future be moldformed to provide an axially disposed opening extending either wholly orpartially therethrough. Thus, the claims of the present invention arenot to be limited solely to wound cartridge rolls.

1 claim:

1. In a grinding tool adapted for use with a grinding element having anend adapted to be progressively worn away by engagement with a workpieceduring operation of said grinding tool, said grinding element beingcharacterized as having an elongated generally cylindrical configurationwith a co-axially extending opening, the combination comprising:

a rotatably supported drive tube, said drive tube being dimensioned tofreely accommodate said grinding element therewithin to removably extendthrough a front end thereof;

a mandrel supported to extend co-axially within said drive tube andhaving a front end portion disposed forwardly of said front end, saidmandrel conforming to said grinding element opening, whereby to permitsaid grinding element to be slideably supported on said mandrel withinsaid drive tube;

means for rotating said drive tube; and

locking means carried by said front end for releasably clamping saidgrinding element intermediate opposite ends thereof for rotation withsaid drive tube, whereby said end of said grinding element normallyprojects forwardly of said front end beyond said locking means andbeyond said front end portion during operation of said tool.

2. In a grinding tool according to claim 1, wherein said locking meansincludes resiliently deformable means for releasably clamping saidgrinding element for rotation with said drive tube and clamping meansfor resiliently deforming said resiliently deformable means.

3. In a grinding tool according to claim 2, wherein saie deformablemeans is a ring member having a through opening dimensioned to slideablyreceive said grinding element, and said clamping means is a generallycup-shaped clamping member internally dimensioned to removably receivesaid ring member and having an opening through a base portion thereofsized to freely receive said grinding element, said clamping memberbeing adjustably threaded onto said drive tube front end for releasablyclamping said ring member axially intermediate said clamping member andsaid drive tube, whereupon said ring member is resiliently deformedradially into clamping engagement with said grinding element.

4. In a grinding tool according to claim 1, wherein said mandrel isremovably supported within said drive tube by means including a sleeveexteriorly dimensioned to be slide fitted within said drive tube andinteriorly dimensioned to freely receive said grinding element, saidsleeve having a front end portion defining a radial surface dimensionedto abut against said front end of said drive tube inwardly of an outersurface thereof, and mounting means for fixedly supporting a rear endportion of said mandrel on a rear end portion of said sleeve, wherebysaid mandrel extends co-axially of said sleeve and has said front endportion thereof arranged forwardly of said front end portion of saidsleeve; and said locking means includes a generally cup-shaped clampingmember and a ring member formed of a resiliently deformable material,said ring member having a through opening dimensioned to slideablyreceive said grinding element, said clamping member being internallydimensioned to removably receive said ring member and said front endportion of said sleeve and having an opening through a base portionthereof sized to freely receive said grinding element, said clampingmember having a rim portion adjustably threaded onto said front end ofsaid drive tube whereby to cooperate therewith to axially clamp saidring member against said front end portion of said sleeve and said frontend portion of said sleeve against said front end of said drive tube,whereupon said ring member is resiliently deformed into clamping surfaceengagement with said grinding element.

5. In a grinding tool according to claim 1, wherein a rear end portionof said mandrel is permanently secured to a rear end of said drive tube6. In a grinding tool adapted for use with generally cylindricalgrinding elements having ends adapted to be progressively worn away byengagement with a workpiece during operation of said grinding tool, atleast certain of said grinding elements being characterized as havinggiven size openings extending axially therethrough, which comprises incombination:

a hollow casing having an opening through a wall thereof;

an elongated drive tube, said drive tube being dimensioned to removablyaccommodate said grinding elements therewithin one at a time to extendthrough a front end thereof;

means for supporting said drive tube for rotation within said casingwith said front end of said drive tube projecting outwardly through saidcasing wall opening;

means for rotating said drive tube;

locking means carried by said front end of said drive tube forreleasably clamping said grinding element intermediate opposite endsthereof for rotation with said drive tube wherein said grinding elementnormally projects forwardly of said front end beyond said locking meansduring operation of said tool; and

adapter means for positionally supporting said certain grinding elementswithin said drive tube, said adapter means including an elongatedmandrel sized to permit slide fitting thereof within said given sizeopenings and means: for mounting said mandrel to extend co-axially ofsaid drive tube from adjacent a rear end thereof with a front endportion of said mandrel projecting forwardly beyond said front end ofsaid drive tube.

7. A grinding tool according to claim 6, wherein said locking meansincludes a cup-shaped clamping member and deformable member formed of aresiliently deformable material, said clamping member being internallydimensioned to removably receive said deformable member and having anopening through a base portion thereof for freely receiving saidgrinding elements, said clamping member being removably fixed to saidfront end of said drive tube for resiliently deforming said deformablemember into clamping surface engagement with said grinding elementwhereby to releasably clamp said grinding element for rotation with saiddrive tube.

8. A grinding tool according to claim 7, wherein said means for mountingsaid mandrel rigidly affixes a rear end portion of said mandrel to saidrear end of said drive tube, and said front end portion of said mandrelprojects forwardly of said drive tube at least sufficiently to beaxially coextensive with said deformable member.

9. A grinding tool according to claim 7, wherein said means for mountingsaid mandrel includes a sleeve slideably insertable within said drivetube and means rigidly connecting a rear end portion of said mandrel toa rear end portion of said sleeve, said sleeve having a front endportion defining a radial surface engageable with a radial surface ofsaid front end of said drive tube inwardly of an outer surface thereof,said deformable member being arranged axially intermediate said baseportion of said clamping member and said front end portion of saidsleeve, and said front end portion of said mandrel projects forwardly ofsaid drive tube at least sufficiently to be axially coextensive withsaid deformable member.

10. An adapter for use with a grinding tool of the type employingelongated, generally cylindrical grinding elements, said tool includinga rotatably supported drive tube internally dimensioned to removablyslide fit support a given maximum diameter grinding element to projectthrough a front end thereof, means for rotating said drive tube, andlocking means carried by said front end for releasably clamping saidgrinding elements intermediate opposite ends thereof for rotation withsaid drive tube, whereby when an end of any of said grinding elementsprojecting from said front end of said drive tube and beyond saidlocking means becomes worn said locking means may be released to allowan additional length of such grinding elements to be withdrawn fromwithin said drive tube, said adapter accommodating said drive tube toprovide support for certain of said grinding elements having diameterssmaller than said given maximum diameter and which are additionallycharacterized as having a common sized axially extending opening, saidadapter comprising:

a sleeve dimensioned to be removably slide fit supported concentricallywithin said drive tube and having means for coupling same for rotationwith said drive tube;

an elongated mandrel; and

means to fix a rear end portion of said mandrel to a rear end portion ofsaid sleeve whereby said mandrel is disposed to freely extend co-axiallywithin said sleeve for rotation therewith, said mandrel having a frontend portion projecting forwardly beyond a front end of said sleeve andsaid mandrel being sized to be slide fitted within said common sizedopening whereby to afford interior support for said certain smallerdiameter grinding elements.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3858362Dated January 7, 1975 Walter N. Welsch Iuventor(s) It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 2 line 21, "my" should read any Column 4, line 24, "inert" shouldread 1- insert Column 4, line 65, "gripping" should read grinding Column5, line 57, "saie" should read said Signed and sealed this 2 3th day ofJune U375.

C. ZEARS IALL DANE? R Til C. MASON Commissioner of Patents attesting,Qfficer and Trademarks ORM Po-1oso (10-69) USCiOMM-DC eoa'le-pes U.S.GOVERNMENT PRINYING OFFICE: 869- 93 o

1. In a grinding tool adapted for use with a grinding element having anend adapted to be progressively worn away by engagement with a workpieceduring operation of said grinding tool, said grinding element beingcharacterized as having an elongated generally cylindrical configurationwith a co-axIally extending opening, the combination comprising: arotatably supported drive tube, said drive tube being dimensioned tofreely accommodate said grinding element therewithin to removably extendthrough a front end thereof; a mandrel supported to extend co-axiallywithin said drive tube and having a front end portion disposed forwardlyof said front end, said mandrel conforming to said grinding elementopening, whereby to permit said grinding element to be slideablysupported on said mandrel within said drive tube; means for rotatingsaid drive tube; and locking means carried by said front end forreleasably clamping said grinding element intermediate opposite endsthereof for rotation with said drive tube, whereby said end of saidgrinding element normally projects forwardly of said front end beyondsaid locking means and beyond said front end portion during operation ofsaid tool.
 2. In a grinding tool according to claim 1, wherein saidlocking means includes resiliently deformable means for releasablyclamping said grinding element for rotation with said drive tube andclamping means for resiliently deforming said resiliently deformablemeans.
 3. In a grinding tool according to claim 2, wherein saiedeformable means is a ring member having a through opening dimensionedto slideably receive said grinding element, and said clamping means is agenerally cup-shaped clamping member internally dimensioned to removablyreceive said ring member and having an opening through a base portionthereof sized to freely receive said grinding element, said clampingmember being adjustably threaded onto said drive tube front end forreleasably clamping said ring member axially intermediate said clampingmember and said drive tube, whereupon said ring member is resilientlydeformed radially into clamping engagement with said grinding element.4. In a grinding tool according to claim 1, wherein said mandrel isremovably supported within said drive tube by means including a sleeveexteriorly dimensioned to be slide fitted within said drive tube andinteriorly dimensioned to freely receive said grinding element, saidsleeve having a front end portion defining a radial surface dimensionedto abut against said front end of said drive tube inwardly of an outersurface thereof, and mounting means for fixedly supporting a rear endportion of said mandrel on a rear end portion of said sleeve, wherebysaid mandrel extends co-axially of said sleeve and has said front endportion thereof arranged forwardly of said front end portion of saidsleeve; and said locking means includes a generally cup-shaped clampingmember and a ring member formed of a resiliently deformable material,said ring member having a through opening dimensioned to slideablyreceive said grinding element, said clamping member being internallydimensioned to removably receive said ring member and said front endportion of said sleeve and having an opening through a base portionthereof sized to freely receive said grinding element, said clampingmember having a rim portion adjustably threaded onto said front end ofsaid drive tube whereby to cooperate therewith to axially clamp saidring member against said front end portion of said sleeve and said frontend portion of said sleeve against said front end of said drive tube,whereupon said ring member is resiliently deformed into clamping surfaceengagement with said grinding element.
 5. In a grinding tool accordingto claim 1, wherein a rear end portion of said mandrel is permanentlysecured to a rear end of said drive tube.
 6. In a grinding tool adaptedfor use with generally cylindrical grinding elements having ends adaptedto be progressively worn away by engagement with a workpiece duringoperation of said grinding tool, at least certain of said grindingelements being characterized as having given size openings extendingaxially therethrough, which comprises in combination: a hollow casinghaving an opening through a wall thereof; an elongaTed drive tube, saiddrive tube being dimensioned to removably accommodate said grindingelements therewithin one at a time to extend through a front endthereof; means for supporting said drive tube for rotation within saidcasing with said front end of said drive tube projecting outwardlythrough said casing wall opening; means for rotating said drive tube;locking means carried by said front end of said drive tube forreleasably clamping said grinding element intermediate opposite endsthereof for rotation with said drive tube wherein said grinding elementnormally projects forwardly of said front end beyond said locking meansduring operation of said tool; and adapter means for positionallysupporting said certain grinding elements within said drive tube, saidadapter means including an elongated mandrel sized to permit slidefitting thereof within said given size openings and means for mountingsaid mandrel to extend co-axially of said drive tube from adjacent arear end thereof with a front end portion of said mandrel projectingforwardly beyond said front end of said drive tube.
 7. A grinding toolaccording to claim 6, wherein said locking means includes a cup-shapedclamping member and deformable member formed of a resiliently deformablematerial, said clamping member being internally dimensioned to removablyreceive said deformable member and having an opening through a baseportion thereof for freely receiving said grinding elements, saidclamping member being removably fixed to said front end of said drivetube for resiliently deforming said deformable member into clampingsurface engagement with said grinding element whereby to releasablyclamp said grinding element for rotation with said drive tube.
 8. Agrinding tool according to claim 7, wherein said means for mounting saidmandrel rigidly affixes a rear end portion of said mandrel to said rearend of said drive tube, and said front end portion of said mandrelprojects forwardly of said drive tube at least sufficiently to beaxially coextensive with said deformable member.
 9. A grinding toolaccording to claim 7, wherein said means for mounting said mandrelincludes a sleeve slideably insertable within said drive tube and meansrigidly connecting a rear end portion of said mandrel to a rear endportion of said sleeve, said sleeve having a front end portion defininga radial surface engageable with a radial surface of said front end ofsaid drive tube inwardly of an outer surface thereof, said deformablemember being arranged axially intermediate said base portion of saidclamping member and said front end portion of said sleeve, and saidfront end portion of said mandrel projects forwardly of said drive tubeat least sufficiently to be axially coextensive with said deformablemember.
 10. An adapter for use with a grinding tool of the typeemploying elongated, generally cylindrical grinding elements, said toolincluding a rotatably supported drive tube internally dimensioned toremovably slide fit support a given maximum diameter grinding element toproject through a front end thereof, means for rotating said drive tube,and locking means carried by said front end for releasably clamping saidgrinding elements intermediate opposite ends thereof for rotation withsaid drive tube, whereby when an end of any of said grinding elementsprojecting from said front end of said drive tube and beyond saidlocking means becomes worn said locking means may be released to allowan additional length of such grinding elements to be withdrawn fromwithin said drive tube, said adapter accommodating said drive tube toprovide support for certain of said grinding elements having diameterssmaller than said given maximum diameter and which are additionallycharacterized as having a common sized axially extending opening, saidadapter comprising: a sleeve dimensioned to be removably slide fitsupported concentrically within said drive tube and having means forcoupling same for rotation with saiD drive tube; an elongated mandrel;and means to fix a rear end portion of said mandrel to a rear endportion of said sleeve whereby said mandrel is disposed to freely extendco-axially within said sleeve for rotation therewith, said mandrelhaving a front end portion projecting forwardly beyond a front end ofsaid sleeve and said mandrel being sized to be slide fitted within saidcommon sized opening whereby to afford interior support for said certainsmaller diameter grinding elements.